I had my car in the shop and the repairs were to take 7 to 10 days and my insurance co. was paying for a rental car from Enterprise. I was originally given a 2013 G37x w/ 36k miles, but the tranny wasn't shifting smoothly, so they allocated me a 2015 GMC Acadia SLT-2 with 60 miles. 7 days later, I drove the Acadia back to Enterprise where the agents are absolutely shocked that the car now had 2400+ miles on it.
That was an exception though. In my book, Unlimited means unlimited. a Quarter of my Hertz rentals get ~1000 miles over 3 days and the other 3/4 of my rentals get between 120 and 200 miles/day. Been renting with Hertz for maybe a year now with no problems *Knock On Wood* I wouldn't even tell Hertz that I'm taking the car to Florida as long as there are no restrictions on your contract on mileage or states it can be driven in.